White-nose syndrome is blamed for the deaths of six million bats in 27 states and five Canadian provinces since 2006. In some places where the fungus outbreak has taken hold, 90% of the bats have died.

“We anticipated that this day would come. It’s not unexpected. But it’s still a sad day,” says Dan O’Brien, a state wildlife veterinarian. “Once this fungus gets into a bat hibernacula it’s going to be there, current evidence suggests, for a long time.”

The fungal disease could have a big impact on Michigan’s economy. Wildlife biologists estimate bats have a roughly $1 billion impact on the state’s agriculture industry by eating harmful insects.

State wildlife officials plan to try to limit human access to caves and other places bats hibernate to limit stress on the bats and slow the spread of the fungal disease.